This is an open-lavel, noncomparative, add-on therapy, extension study in patient who have previously participated in a tiagabine HCL epilepsy study. However, during the course of the study concomitant AEDs may be gradually withdrawn so that some patients may be expected to achieve tiagabine HCL monotherapy. This study may be conducted at any site that is conducting or has conducted, tiagabin HCL clinical studies in the United States. The objective of this study is to determine the safety of tiagabine HCl as chronic therapy for epilepsy.